MCP73871 click

PID: MIKROE-2858

Weight:25 g

MCP73871 click is a fully integrated solution for system power delivery and Li-Po/Li-Ion battery charge management. The click features many Li-Po/Li-Ion battery charging optimizations, used to maximize the battery life. Some of the MCP73871 click features include constant current and voltage charging algorithms, overvoltage protection, automatic end of charge control, automatic recharge feature, preconditioning for depleted cells and thermal management.

Table of contents

The features this device has, coupled with the ability to simultaneously power up the system load and charge the connected battery, make this click a perfect solution for powering up many different battery-operated builds and projects, which use a rechargeable Li-Po/Li-Ion battery, but can also switch to an external power source.

How does it work

MCP73871 click uses the MCP73871 device, a system load sharing and Li-Po/Li-Ion battery charge management integrated circuit from Microchip. This device completely manages the power distribution, utilizing many different steps in this process.

The input voltage is constantly monitored and with no battery connected or with a battery element which is deeply depleted, the power to the connected load will be delivered straight from the external power supply, provided from the 5V rail of the mikroBUS™ socket. The current that can be delivered in this mode, depends on the limiting factor selected by the PRG2 pin. If the PRG2 pin is set to a LOW logic level, the current will be limited to 80mA - 100mA. If the PRG2 pin is set to a HIGH logic level, the current supplied to the load will be limited to 400mA - 500mA.

There are several conditions set by the MCP73871 device, that define the behavior of the power management logic. If there is a Li-Po/Li-Ion battery connected to the battery connector, the charging procedure will go through the following steps:

If the connected battery is deeply depleted and the CE (Charge Enable) pin is set to a HIGH logic level, the preconditioning mode is activated. The charging current is only a fraction of the regulated charging current, used for fast charging, preventing battery damage and overheating.

If the battery voltage is above the preconditioning threshold voltage set by the MCP73871 device, the fast charging will begin, and the charging current is set by the PRG2 pin, like described above and a voltage equal to 4.35V, as per factory settings of the MCP73871 IC.

When the charging complete conditions are met, the charger circuit will stop the charging process. The battery voltage is monitored, and when it falls under the recharge threshold, another charging cycle will be repeated.

During all the charging modes, the temperature of the MCP73871 die is monitored, so the charging current is regulated accordingly. The overtemperature protection will put the device in the shutdown mode, preventing damage.

If the Timer is enabled by the TE pin, it will be used to limit the charging time, if the battery voltage never reaches the end-of-charge condition.

The MCP73871 power-sharing system logic, enables to simultaneously charge and power up the system load, connected to the onboard output screw terminal. The power-sharing system is active at all times and always prioritizes connected load over the battery charging. Li-Po/Li-Ion battery can be connected to the onboard 2.54mm two-pin header. There are three LEDs that are used to indicate power good status, as well as the charging status. The status LED signalization is explained in the Status LED table, below.

Specifications

Type

Battery charger

Applications

A perfect solution for powering up many different battery-operated builds and projects, which are powered up by a rechargeable Li-Po/Li-Ion battery, but can also switch to an external power source while charging the battery.

Ability to simultaneously power up the system load and charge the connected Li-Ion/Li-Po battery by applying optimized battery charging algorithm.

Interface

GPIO

Input Voltage

5V

Click board size

M (42.9 x 25.4 mm)

Pinout diagram

This table shows how the pinout on MCP73871 click corresponds to the pinout on the mikroBUS™ socket (the latter shown in the two middle columns).

Notes

Pin

Pin

Notes

Set Charging Current

PG2

1

AN

PWM

16

TE

Enable Safety Timer

NC

2

RST

INT

15

NC

Charge Enable

CE

3

CS

RX

14

NC

NC

4

SCK

TX

13

NC

NC

5

MISO

SCL

12

NC

NC

6

MOSI

SDA

11

NC

NC

7

3.3V

5V

10

+5V

Power Supply

Ground

GND

8

GND

GND

9

GND

Ground

MCP73871 click electrical specifications

Description

Min

Typ

Max

Unit

Charge Current (if PG2 is low)

80

100

mA

Charge current (if PG2 is high)

400

500

mA

Onboard settings and indicators

Label

Name

Default

Description

LD1

PWR

-

Power LED indicator, green

LD2

PG

-

Power good LED, blue

LD3

STAT2

-

Status LED, green

LD4

STAT1

-

Status LED, red

J1

VBAT

-

Battery connector

TB1

VOUT

-

External load connector

Status LEDs table

Charge Cycle State

STAT1

STAT2

PG

Shutdown (VCC=VBAT)

Off

Off

Off

Shutdown (CE=L)

Off

Off

On

Preconditioning

On

Off

On

Constant Current

On

Off

On

Constant Voltage

On

Off

On

Charge Complete - Standby

Off

On

On

Temperature Fault

On

On

On

Timer Fault

On

On

On

Low Battery Output

On

Off

Off

No Battery Present

Off

Off

On

No Input Power Present

Off

Off

Off

Software support

We provide a library for MCP73871 click on our LibStock page, as well as a demo application (example), developed using MikroElektronika compilers. The demo can run on all the main MikroElektronika development boards.